1. Field of the Invention
The present invention relates generally to rectangular box cartons that open by lifting a hinged top or cover panel and a blank for forming such a carton. More particularly, the present invention relates to a "flip-top" rectangular box carton in which the cover panel is connected to a closure panel that seals the carton. The cover panel also has endwall insertion panels that may be inserted in the endwalls but are not glued in position.
2. Description of the Prior Art
Cartons for ice creams and other frozen desserts generally are made in half-gallon sizes and in one of two shapes: round boxes or rectangular boxes. In the rectangular box shape, the carton usually comes in one of two styles. First, it may be formed from an unglued blank shaped on a mandrel, then glued at its four corners. The resulting open-top box is filled through the wide opening at the top, then the hood or cover is sealed around the upper perimeter of the box. This forms a large "flip top" opening for the customer, a carton configuration referred to as the "Kliklok" style structure, named for the machinery used to form and close the carton. Second, rectangular box cartons may be preglued along a glue flap at one long edge, then filled from a small end opening. In this case, the glue flap (along one of the long edges) of the carton acts as the opener or one of the end flaps is lifted to open the carton. The end flaps are usually locked (but not sealed) by interlocking flap notches. While opening the carton at the glue flap gives a large "flip top" type opening, this opening cannot be easily reclosed. An opening at the locked end flaps provides reclosing capability, but the smaller opening is less convenient for dipping. Accordingly, the "flip-top" type opening is usually preferred, particularly when the hinged cover panel has, after opening, associated panels folded downward at ninety degrees around its free edges to help hold the cover panel down after reclosing.
The conventional equipment that locks the ends of rectangular cartons is fairly simple and has been in existence for many years (e.g., Anderson Model No. 555, made by APV Anderson Brothers Inc., 1303 Samuelson Road, Rockford, Ill. 61109). Many dairies have more than one such item of equipment in their plants. Recently, an inexpensive attachment that seals carton ends (primarily for tamper evidence) instead of locking them has also become available, but no adapter yet exists that permits the older equipment, augmented by the end sealer, to make a reclosable flip top or hooded carton of the first style discussed above. New equipment that can both form flip top cartons and also seal the ends is available but costly; it currently requires completely replacing the older equipment that is in the dairy and therefore involves a considerable investment. Often dairies are not in a position to replace their efficient, simple machines with the more expensive, complex ones, strictly to have carton ends glued and to provide a flip top or hooded opening for dispensing the ice cream or other product.
U.S. Pat. No. 4,773,542 shows a carton design that has a reclosable flip top and can be processed on conventional packaging equipment augmented by a sealing attachment. The present design is intended to improve on the design of U.S. Pat. No. 4,773,542 by providing a more efficient opening structure and additional sealing of the ends.
Most flip top or hooded rectangular box ice cream cartons have one of two types of opening devices:
(a) an outside glue flap glued to the front panel that is lifted and separated from the front panel upon opening; or
(b) an outside glue flap formed with cuts for a tear strip and glued to the front panel so that removal of the tear strip severs the outside glue flap.
In an opening device of the first type, the glue flap often does not separate at the proper location or it delaminates, forming a web that can block access to the carton contents. A tear strip, on the other hand, often breaks before complete tearing across the glue flap. The opening failures are all too frequent with ice-cream cartons, because of the high moisture and low temperature conditions to which the cartons are necessarily subjected. In addition, the tear strip cuts weaken the glue flap during handling of the empty carton for filling, sometimes causing the carton to bend at these cuts rather than the bend score connection to the top panel. This bending causes machine jams during filling operations.
Accordingly, what is needed to improve the prior art is a carton design processable on conventional packaging equipment with end flaps and glue flaps configured for the standard folding sequence and with a simple, reliable opening device to allow the customer to easily open the carton and to dispense ice cream through a flip-top closure. In addition, it is desirable to be able to seal the ends of any such new carton by utilizing an economical sealing attachment with the conventional end-locking rectangular carton packaging equipment. Such equipment characteristically folds end flaps in the following order: bottom, top, back, front (carton viewed in normal position for flipping top open).